// CodeMirror, copyright (c) by Marijn Haverbeke and others
// Distributed under an MIT license: http://codemirror.net/LICENSE

// Utility function that allows modes to be combined. The mode given
// as the base argument takes care of most of the normal mode
// functionality, but a second (typically simple) mode is used, which
// can override the style of text. Both modes get to parse all of the
// text, but when both assign a non-null style to a piece of code, the
// overlay wins, unless the combine argument was true and not overridden,
// or state.overlay.combineTokens was true, in which case the styles are
// combined.
/**
 * @modifier NHN FE Development Lab <dl_javascript@nhn.com>
 */
import CodeMirror from 'codemirror';

/*eslint-disable */
CodeMirror.overlayMode = function(base, overlay, combine) {
  return {
    startState: function() {
      return {
        base: CodeMirror.startState(base),
        overlay: CodeMirror.startState(overlay),
        basePos: 0,
        baseCur: null,
        overlayPos: 0,
        overlayCur: null,
        streamSeen: null
      };
    },
    copyState: function(state) {
      return {
        base: CodeMirror.copyState(base, state.base),
        overlay: CodeMirror.copyState(overlay, state.overlay),
        basePos: state.basePos,
        baseCur: null,
        overlayPos: state.overlayPos,
        overlayCur: null
      };
    },

    token: function(stream, state) {
      if (stream != state.streamSeen || Math.min(state.basePos, state.overlayPos) < stream.start) {
        state.streamSeen = stream;
        state.basePos = state.overlayPos = stream.start;
      }

      if (stream.start == state.basePos) {
        state.baseCur = base.token(stream, state.base);
        state.basePos = stream.pos;
      }
      if (stream.start == state.overlayPos) {
        stream.pos = stream.start;
        state.overlayCur = overlay.token(stream, state.overlay);
        state.overlayPos = stream.pos;
      }
      stream.pos = Math.min(state.basePos, state.overlayPos);

      // state.overlay.combineTokens always takes precedence over combine,
      // unless set to null
      if (state.overlayCur == null) return state.baseCur;
      else if (
        (state.baseCur != null && state.overlay.combineTokens) ||
        (combine && state.overlay.combineTokens == null)
      )
        return state.baseCur + ' ' + state.overlayCur;
      else return state.overlayCur;
    },

    indent:
      base.indent &&
      function(state, textAfter) {
        return base.indent(state.base, textAfter);
      },
    electricChars: base.electricChars,

    innerMode: function(state) {
      return { state: state.base, mode: base };
    },

    blankLine: function(state) {
      if (base.blankLine) base.blankLine(state.base);
      if (overlay.blankLine) overlay.blankLine(state.overlay);
    }
  };
};
